Flexible Tactile-Sensing Gripper Design and Excessive Force Protection Function for Endovascular Surgery Robots

Abstract

Research on endovascular surgery robots (ESR) is continuously developing, because ESR can protect surgeons from radiation exposure. For designing an ESR manipulator, the main challenge is controlling the soft surgical tools and measuring the endovascular stress simultaneously. In this letter, a flexible tactile-sensing gripper (FTG) is designed to realize the stable grasping of the surgical catheter and the tactile sensing of catheter force. Firstly, a catheter grasping model was constructed, and the factors affecting the force measurement were quantitatively analyzed. Secondly, the simulation experiments based on FTG models with three different sizes were implemented. When the catheter force was too large, shrinking the grasping distance of FTG can avoid the surgical risk. This method protected the surgeon's behavior and controlled the catheter force at the same time, which was called excessive force protection function (EFPF). Thirdly, based on simulation results, we made a FTG prototype which meet the surgical requirements and integrated it into an ESR manipulator. This manipulator could measure the catheter forces by detecting the coordinate change of marking points on FTG surface. The calibrated FTG prototype got average and maximum errors of force sensing approximately 37 mN and 223 mN, respectively. Finally, the proposed EFPF is evaluated. In the experiment of carotid artery catheterization, EFPF controlled the catheter force within 393 mN, which was far less than the control group's 1351 mN.